What
is "full spectrum" light?
There are perceived differences in the "quality"
of light produced by electric light bulbs. The term
"full spectrum light " is a marketing designation
used to highlight a couple of these differences. However,
the term does not have a precise technical definition.
"Full spectrum" electric light is commonly
understood to be light that is similar to "daylight"
in two ways. One, the light is perceived to have the
bluish white appearance and brightness values of daylight
and, two, the light has strong color rendering capabilities.
Daylight is a form of radiant energy that travels in
waves. These waves have a length. In the visible part
of the light spectrum, shorter length waves produce
a light that appears blue to the human eye. Longer waves
produce a light that appears red. The rainbow is nature's
way of revealing all the colors (and wavelengths) of
daylight. Since daylight includes all wavelengths in
the visible spectrum, it represents "full color¨
or the "full spectrum¨. To the human eye daylight
is perceived to have a bluish white color. It is also
perceived as having a strong brightness value.
Electric light bulbs (often fluorescent) can be manufactured
to produce light that simulates the bluish white color
and perceived brightness of daylight. A daylight bulb
is mimicking the color of light from the sky, not the
direct beam of the sun. These bulbs are often marketed
as "full spectrum¨ or "daylight¨ bulbs
but there are also bulbs not marketed as "full
spectrum¨ that produce the same bluish white color appearance
and perceived brightness of daylight. Many of these
bulbs also do an excellent job at accurate color rendering.
More on related topics: color
temperature and color rendering
index.
What are the benefits of "full spectrum¨
or daylight simulated illumination?
Psychological. Most people prefer
daylight from windows and skylights to electric light.
Daylight gives people a positive feeling and can help
improve mood and motivation. Because "full spectrum"
light bulbs produce the appearance of white or bluish-white
light and because they also produce a higher perception
of brightness, there is often a positive association
with daylight. Any bulb with a color
temperature of 5000K or higher will produce
light perceived by most people as similar to daylight.
Incandescent bulbs coated with neodymium
do not have a color temperature of 5000K or higher,
but they provide this same positive association with
daylight by filtering out the yellow cast common from
standard incandescent light bulbs. Neodymium bulbs also
tend to make blues and reds appear richer. Above find
bulbs with a color temperature of 5000K or higher and
neodymium light bulbs offered by Topbulb. (See a more
detailed explanation of color
temperature.)
Health. Full spectrum light therapy
is sometimes recommended for people suffering from seasonal
affective disorder (SAD). Research shows that any light
source (preferrably daylight) at 10,000 lux (1000 footcandles)
aimed toward the eye for 30 minutes a day, can be effective.
Light sources with a strong blue wavelength component
are most effective. "Full spectrum" lights
usually meet this standard. Any electric light bulb
with a "color temperature" of 5000K or higher
also meets this standard. Above find a list of bulbs
offered by Topbulb with a color temperature of 5000K
or higher and light bulbs labeled by the manufacturer
as "full spectrum". (See more detailed explanations
of color temperature and
seasonal affective disorder.)
Color. Daylight provides the highest
level of accurate color rendering. Most incandescent
and halogen light bulbs produce light that is excellent
at color rendering. However, they usually do not also
produce the bluish white light associated with daylight.
"Full spectrum" light sources, usually fluorescent,
often attempt to provide both excellent color rendering
and light that appears similar to daylight.
The lighting industry uses a value called the Color
Rendering Index (CRI) to describe the ability of a light
source to render colors. The higher the number, on a
scale up to 100, the better the light source for accurate
color rendering. By definition, daylight and incandescent
light sources have a CRI of 100. Typically, fluorescent,
HID and other light sources have lower CRIs. However,
these same bulbs can be manufactured with CRIs of 90
or higher. Many light bulbs marketed as "full spectrum"
have a CRI of 90 or higher (note that neodymium bulbs
do not have high CRIs). When color identification is
important such as in graphic arts, museums, color printing
and the fabric industry, high CRI illumination is beneficial.
There are many non-incandescent light bulbs that provide
CRIs of 90 or higher. Above you will find a list of
these bulbs offered by Topbulb. (See a more detailed
explanation of color rendering index
(CRI).)
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